Renewable electric fuse



Jan. 13, 1931. v F. c. LA MAR I 1,

RENEWABLE ELECTRIC FUSE Filed Jan. 5, 1927 Mill-"wi l 1 nvmvron ayg awhe ATTORNEY U N j PATENT oFF cs rRANKcLa Man, or 'rrr rsnunon.rnnnsrnvlmin; Assrenon pro GREAT wns'rnnn ruse COMPANY,FPITTSBURGH-1,.PENNSYLVANIA, A conrona'rron or DELAWARE RE E ABLEnnn'o'rnrc rusE Application filed January 5, 1927. Serial No. 159,079.,V

More particularly invention relatesfto:

ferrule-type fuses.

In electricfuses when the fusible element or reload is fused or burnsout gases are 6 generated in considerable volume and at h ghtemperatures and such gases carryin "suspension particles of: the fusedmetal. 4

nowincommon use is the tendency toward a' 10' concentrated escapeiof.thegasesaxially of the fuse, frequently resulting in welding. the partsof the;mechanismftogethereither by fusion or by thedeposit ofthemetallic particles. .Thus'the cap'may be fixed'to the i ferrule ortheanchoringdisk maybefixed toleither or both, so as to be removable,.ifat all, after a great deal. of .trouble 1 or the extremity of thefusibleelement may be welded to the anchoring disk or ferrule to both. iY

20,. Escape of thegasesformedby fusion of the fusible elementmust, ofcourse, be provided for to prevent-rupture of-the fuse which wouldprevent its reuse, but a concentrated escape must be, avoided:toyprevent the objectionable occurrences above mentioned.

My object therefore isto soiimprovethe constructionof renewable ferrulefuses theta restricted and :Widely distributed escape isv provided-forthe gases, and thelmaterialdes .0 positof' the metal particles on theparts in movable relation is avoided.) 7 l 7 i 1 Thus I provide means,whereby afrestricted escapefor a portion of the gases is provided aroundthe perimeter of thewasher which 7 between the cap and therferrule.

anchors the end of the fusible element and -I also provide means forbaflling'a portion of the gases before they leave ,the ferrul eto causethe deposit of the metallic particles be- 14 fore they reach thepa-rtsin movable relation.

Other novel features of construction, and also of arrangement; of parts,will appear from the followingdescription.-

, Inthe accompanying drawings, wherein I have 'illustratedthe bestembodiment of the principles of my invention now known tome, Fig. l isan elevation of a renewableferrule fuse partially broken away inlongitudinal section to show the internal-parts; Fig. 2 is a similarview. but turnedninety degrees from 1;:Fig. 3 is an enlarged diametricsection of one of the ferrules, its anchoring disk andcap, the ferrulebeing slightly modifled in construction from that shown in Figs.

1 and 2; Fig. 4 is a perspective of the anchoring disk; Fig.5 isaviews'imilarto Fig. 3but i showing a modificationwherein the bafile is TAfaultof the-typesof renewable fuses.

a separate element from the ferrule-and Fig. Q

'6 is an elevation of thebafileshown in Fig. 5. 1 Referring first toFigs. 1 and 2, l-repreeach end of the 'shelll is fixed a metal, usuallybrass, ferrule 3. 9 The ends of the shell 2 are preferably provided withnotches 2a to prevent a sealingcontact between the end of the shell andthe ferrule." The inner end of theiferrule' is provided with internalthreads which screw onto the external threads of the end of the shell 1.The outer end of the ferrule 3 is of reduced external diameter, thusforming an intermediate circumferential shoulder 4. if I Theouter endofthe ferrule is provided with exterior threads 5' upon" which arescrewed the interior threads 6 ofthe metal 8 cap '7which is preferablyalsoof brass. At

either? end of the threaded portion 5'ofthe ferrule 3 is a plane annularsurface of "the 1 and 2 said shoulder or bafiie 9 is disposed in a planeat right angles to' the axis of the shell and -ferrule, whi1e in Fig. .3said shoulder. .or baffle is frusto-conical'in shape BX-.

tending inwardly of the shell .1.

I The boreof theferrule outwardly from the shoulder isofprogressivelyincreasing diameter forthe purpose "of giving so depth ofthe threads-which surfaces form 1 with the skirt'of thefcap annularchambers '8 at the extremitiesrof the threadedengageclearance for theangularity of the fusible element 2 and to better distribute the gaseswhich may pass outwardly through the throat 10.

At the outer end the bore of the ferrule 3 is countersunk-to form adisk-seatwhose inner end is the annular shoulder 11 and its side theannular wall 12.

13 is the disk which is employed to anchor the end of the fusibleelementQ, the disk be ingprovided withan eccentrically positioned slot14 through which theiextremity of the fusible element is inserted,saidextremity being then bent-down flat against the exterior surface of thedisk, as shown. In

assembling the fuse,- the disks are positioned.

with-their slots disposedat opposite sides of theaxial line of the fuse,thus causingthe' angularity-in'the disposal of the fusible element-shownin the drawings.

The disk 13 is of proper, diameter to fit looselylin its seat and is setoutwardly in the same byvmeans of its struck-out toes 15 which rest onthe shoulder 11. Thus there is provided a restricted escape for the:gases around the perimeter of the disk 13 and between'it and theferrule.

.The .disk preferably protrudes slightly from the end of the ferrule andwhen the cap 7 is'screwed into place, it clamps the bentover extremityof the fusible'element betweenit and the disk: and also clamps the.

disk to "the ferrule. The end'of the cap 7 is spaced away from the endof the ferrule. The skirt of the cap 7is shortenough to inslurezla spacebetween it and the ferrule shoulcer It is evident that in case of aburning-out disk and the cap. Furthermore a portion ofthe gases will betrapped by said baffle andwill be diverted and caused to find arestricted: escape betweenthe threads of the shell and the ferrule. T

Thexremainderiof the gases, passing outwardly through the throat 10 willfinda distributed escape around i the. perimeter of the disk 13 and willthen escape through the chambers 8 and between the ferrule 3 and theskirt of the cap 7 between the threadsof the same.

It'is thus evident that there can be no concentrated escape ofthe gasesin such volume as to weld together parts in movable relation nor tocausedanger of fire. At the same timesufiicient of the metal particlesare divertedifrom passing through the throat 10 to prevent such weldingaction through the deposit of such particles. Again, the escape of thegases is so fully provided for that no rupturing of the fuse ispossible.

In Figs. 5 and 6 I show the baffle formed as a separate element 16formed with a per imetral lip 17 which is clamped between the end of theshell 1 and an internal shoulder 18 of the ferrule, while the body ofthe element is of frusto-conical form extending inwardly ofth'e shell1'. In'this case the outer bore'of the' ferrule may be cylindricalinstead of conical.

This modified form is less expensive than that. shown-inthe precedingviews of the drawings, and thus may be regarded as preferable.

What I desire to claim is 1. In a renewable electric fuse, thecombination of a shell of insulating material, a ferrulermounted on theend 0fv the shell, an anchoring disk. bearing against the end of theferrule, the disk being spaced from the end of the ferrule to providefor the escape of gases between the ferrule and the disk, a fusibleelement in the shell and having its end anchored to the'disk, and a capscrewed onto the ferrule and holding the disk in position.

2. In a renewable electric fuse, the combination of a shell ofinsulating material, a ferrule mounted on the end of the shell, the boreof the ferrule being provided with a seat at'its outer end, adiskmounted in said seat, means for spacing the body of the disk out ofcontact With'the ferrule to provide for the escape of gases around thedisk, a fusible element in the shell and anchored to the disk, and a capscrewed onto the ferrule and holding thedisk in position.

3. In a renewable electric fuse, the combination of a shell ofinsulating material, a ferrule permanently mounted'on the end of theshell and provided with an exteriorly threaded portion, an anchoringdisk bearing against the outer end of the ferrule, the ferrule having aninwardly contracting central opening through which the fusible elementextends, a fusible element in the shell having its end anchored to thedisk, and a threaded cap screwed onto the threaded portion of shell andprovided with an exteriorly threaded portion, an anchoring disk bearingagainst the outer end of the ferrule, the ferrule having an inwardlycontracting central opening through which the fusible element extends, afusible element in the shell having its end anchored to the disk, and athreaded cap screwed ontothe threaded portion of the ferrule, and abaflie in saidierrule arranged to divert a portion of the gases offusion and cause them to escape between the portions of the fel ule andthe cap which are in threaded en agement.

igned at Tucson, Arizona, this 24th day of December, 1926.

FRANK 0. LA MAR.

